I have to say that these American Cartoons are miles ahead of the Japanese anime and Manga cartoons. One Piece, Pokemon, Bleach, etc.

Maybe some Americans just want more adult Cartoons?

There were more cartoons that were better in the past than there are today. Cartoons today are getting pretty crappy. We have Family Guy, American Dad, The Regular Show, Adventure Time(which I've never seen,) Home Movies, but what else is really good?

In Japan, while I don't watch a lot of what is released now days, they have a constant stream of new animes and I've heard that a lot of them are good. Attack on Titan is an example of a newer one.